A communication method and apparatus is disclosed that uses a received signal strength indicator (RSSI). In a sensor network including a plurality of nodes, a first node of the plurality of nodes receives a signal transmitted from a second node of the plurality of nodes, at least once. The first node also manages a link state with the second node according to the RSSI of the received signal. Therefore, the first node can receive signals from the plurality of nodes and then predict whether the second node moves. The first node can also predict a link state after the second node is moved so that communication can be performed through a link in a good state. Accordingly, the communication quality and the network performance of a network are enhanced.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A communication method in a sensor network including a plurality of nodes, comprising: receiving, by a first node of the plurality of nodes, a signal from a second node, at least once; and managing, by the first node, a link state with the second node according to a received signal strength indicator (RSSI) of the received signal, said managing comprising: storing RSSIs of the plurality of nodes, based on signal-received times; and predicting link states using the stored RSSIs, said predicting the link states comprises: estimating a distance between the first node and the second node, a moving speed of the second node, and a moving start time point of the second node, wherein the moving start time point of the second node is estimated by averaging a time point when the signal is received in a final stationary state and a time point when the signal is received in a first moving state; and determining whether the second node moves; and communicating, by the first node with the second node according to a link state.
2. The communication method of claim 1 , wherein the distance between the first node and the second node is estimated by a relationship wherein the RSSI of the received signal is inversely proportional to a square of a distance between the first and second nodes.
3. The communication method of claim 1 , wherein determining whether the second node moves by determining whether the RSSI of the received signal has changed according to a time that the signal is received.
4. The communication method of claim 1 wherein the first node predicts that the second node moves away from the first node when the RSSI is reduced according to the signal-received time, and that the second node moves closer to the first node if the RSSI is increased according to the signal-received time.
5. The communication method of claim 1 , wherein, if the second node moves out of a transmission range of the first node, the first node does not transmit a message to establish a route to the second node during the communication.
6. The communication method of claim 1 , wherein, if the second node moves out of a transmission range of the first node and the first node receives a message to establish a route from the second node, the first node does not transmit the received message to the second node.
7. The communication method of claim 1 , wherein , if the second node moves out of a transmission range of the first node then the first node communicates through a relay node to the second node, wherein the relay node is located within the transmission range of the first node and the second node.
8. A communication apparatus in a sensor network comprising a plurality of nodes, wherein a first node of the plurality of nodes receives a signal transmitted from a second node of the plurality of nodes, at least once, and manages a link state with the second node according to a received signal strength indicator (RSSI) of the received signal, wherein the first node stores RSSIs of the plurality of nodes, based on signal-received times and predicts the link state using the RSSIs, wherein predicting the link state comprises; estimating, by the first node, a distance between the first node and the second node, a moving speed of the second node, and a moving start time point of the second node, and determining whether the second node moves, wherein the first node estimates the moving start time point of the second node by averaging a time point when the signal is received in a final stationary state and a time point when the signal is received in a first moving state, wherein the first node communicates with the second node according to the link state.
9. The communication apparatus of claim 8 , wherein the first node estimates the distance between the first node and the other node, using the relationship where a value of the RSSI of the received signal is inversely proportional to square of a distance between the first and second nodes.
10. The communication apparatus of claim 8 , wherein the first node concludes that the second node moves if the value of the RSSI of the received signal is changed according to the time that the signal is received.
11. The communication apparatus of claim 8 , wherein the first node determines that the second node is moving away from the first node if the value of the RSSI is reduced according to the signal-received time, and that the second node is moving closer to the first node if the value of the RSSI is increased according to the signal-received time.
12. The communication apparatus of claim 8 , wherein, if the link state with the second node is weak, the first node does not transmit a message to establish a route to the second node.
13. The communication apparatus of claim 8 , wherein, if the second node moves out of a transmission range of the first node and the first node receives a message to establish a route from the second node, the first node does not transmit the received message to the other nodes.
14. The communication apparatus of claim 8 , wherein if the second node moves out of a transmission range of the first node then the first node communicates with the second node through a relay node wherein the relay node is located within the transmission range of the first node and the second node.
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February 13, 2009
May 8, 2012
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